France’s nuclear wastes must be secured for over 100,000 years

The repositories are supposed to remain hermetically sealed for at least 100,000 years — roughly the length of time human beings have existed on Earth

Europeans Pursue Labyrinths of Nuclear Waste, NYTimes.com, By SUE LANDAU : June 2, 2011 BURE, FRANCE — Reached by narrow roads that meander through picturesque villages, a high-tech laboratory sits in a corner of France so remote that until construction started on it a decade ago, the local inn was not connected to the electricity grid.

Beneath a plateau surrounded by fields of colza and wheat, the underground laboratory, located near the village of Bure, in the eastern French region of Lorraine, is run by the Agence Nationale pour la Gestion des Déchets Radioactifs, or Andra, the national authority charged with the safe disposal of nuclear waste.

The laboratory’s work is to test what might happen if spent nuclear fuel were to be stored permanently in caverns cut deep into rock. France plans to do just that; others are seeking to follow suit…….Europe is poised to enshrine a final solution for its long-term radioactive wastes, the industry’s most persistent public-relations problem.

A directive being debated in Brussels would commit the Continent to following the example of France, Finland and Sweden, which are preparing to dig deep underground labyrinths to store the highly toxic waste forever.

The directive, which is expected to come before the European Parliament on June 22, would oblige all 27 members of the European Union to submit plans to the European Commission, the bloc’s executive arm, for similar nuclear waste repositories deep underground.

Spent fuel is stockpiled at present in interim storage facilities with a life span of 50 years to 100 years, yet some of the elements that it contains remain radioactive for up to a million years.

Scientists have been researching the idea of burying such waste deep in the Earth’s crust for much of the past half century; Finland, Sweden and France decided to go ahead with deep disposal projects about a decade ago.

The task is unlike any other because of the sheer amount of time involved.

Setting up geological repositories takes decades, starting with studies to find a suitable rock structure, and testing the metals that could be used to build waste-storage canisters. Computer models must be constructed to examine how the different substances, and possible environmental variables, would interact over time. Then, the results of the modelling exercise must be tested on site, by tunneling and equipping cavernous galleries, while official authorizations and public support must be won.

Once operational, the repositories will be monitored for 100 years, starting from when spent fuel is first put in. Then they will be sealed for posterity.

The repositories are supposed to remain hermetically sealed for at least 100,000 years — roughly the length of time human beings have existed on Earth — by which time any radioactivity seeping out should be no stronger than the Earth’s own background dose.

The world’s first such repository is expected to become operational in Finland in 2015, the second in Sweden in the early 2020s and the third in France in 2025.

Metal canisters full of spent fuel, which will have already been cooling for years, will be fitted into concrete-lined holes in the tunnel walls. Bentonite clay, a soft medium that traps water, will be packed around the canisters to give an extra layer of protection. As the repository is filled, it will be progressively sealed, using purified clay and concrete, tunnel by tunnel, gallery by gallery….

Europeans Pursue Labyrinths of Nuclear Waste – NYTimes.com